A compelling need exists to find more efficacious medicines with which to treat Chagas? Disease, especially the chronic stages for which there is no effective treatment. Chagas? Disease is caused by a parasitic trypanosome that afflicts millions in the tropical Americas and more than 300,000 in the US. Moreover, with climate change there are changing patterns of parasitic diseases such as Chagas? Disease, and this is certain to affect an increasing number of American citizens in the future. Our laboratories have discovered an exquisitely potent anti-Chagas agent from a marine cyanobacterium that targets the unique protease of this parasite, namely ?cruzain?. Cruzain represents a chemically and genetically validated target within this parasite. Moreover, this natural product as well as synthetic analogs have the ability to clear myoblast cells of infection with no significant host cell cytotoxicity. In this application we plan to advance this drug class to meet this unmet medical need in eukaryotic parasitic diseases, and this will be accomplished in two phases. Three specific aims in the R21 phase will allow synthesis and re-synthesis of several gallinamide A analogs designed previously from a modeling study, establish critical initial PK parameters and allow proof of concept efficacy testing. We have developed an effective synthetic route for this compound as well as 16 analogs based on extensive optimization of two published synthetic routes, insuring an adequate supply of the compounds. This is a rare starting point for a drug development effort in which a natural product can be sustainably produced and the molecular target in the parasite is known. In the R33 phase, we will further explore a second generation of model-inspired gallinamide A analogs through chemical synthesis, expand our evaluation of their ADME, PK, MTD and efficacy evaluations, and then test our best lead compounds in a chronic curative mouse model. A set of clear metrics have been devised by which to evaluate progress and success in both the R21 and R33 phases of the project. At the conclusion of this project, we anticipate delivery of a late stage preclinical lead for the treatment of Chagas? Disease which will have a robust profile of chemical, biochemical, pharmaceutical and efficacy information.